The invention relates to a method of correcting inhomogeneities in MR perfusion images of the myocardium of a patient, which perfusion images relate time-sequentially to a preliminary phase which precedes the administration of a contrast medium and to an examination phase which succeeds the administration of the contrast medium, the perfusion images from the examination phase being corrected, in a correction step, for a detected intensity variation of the perfusion images from the preliminary phase.
MR perfusion images of the myocardium of a patient are formed so as to enable determination of the perfusion thereof. The actual image acquisition takes place after the injection of the contrast medium so as to enable suitable evaluation as to which parts, if any, of the myocardium exhibit insufficient perfusion.
From practice it is known to correct the perfusion images acquired after the administration of the contrast medium in the examination phase for the intensity variation detected in the preceding preliminary phase. This is because the acquired perfusion images exhibit an intensity variation which is dependent inter alia on the position occupied by the heart relative to the acquisition coils of the relevant MR scanner during the exposure. The intensity variation of the perfusion images from the preliminary phase preceding the administration of the contrast medium then serves as a starting point for the correction of the intensity variation of the perfusion images in the examination phase.
In practice, however, the above step often has an effect to the contrary, because the patient is allowed to inhale deeply a few times just before having to hold his or her breath during the administration of the contrast medium. Consequently, the position of the heart in the examination phase changes relative to the position occupied by the heart during the preliminary phase. The correction step executed in conformity with the state of the art, consequently, may give rise to incorrect correction of the intensity of the perfusion images from the examination phase.
It is an object of the invention to solve the latter problem.